import asyncio
from pathlib import Path
from unittest.mock import AsyncMock, patch

import aiosqlite
import pytest

from app.db import (
    _apply_migration,
    _parse_migration_statements,
    init_db,
    open_db,
)


async def test_open_db_applies_hardening_pragmas(tmp_path: Path) -> None:
    database_path = str(tmp_path / "bangui_test.db")
    db = await open_db(database_path)
    try:
        async with db.execute("PRAGMA journal_mode;") as cursor:
            row = await cursor.fetchone()
        assert row is not None and row[0].lower() == "wal"

        async with db.execute("PRAGMA foreign_keys;") as cursor:
            row = await cursor.fetchone()
        assert row is not None and row[0] == 1

        async with db.execute("PRAGMA busy_timeout;") as cursor:
            row = await cursor.fetchone()
        assert row is not None and row[0] == 5000
    finally:
        await db.close()


async def test_open_db_respects_busy_timeout_for_concurrent_writes(tmp_path: Path) -> None:
    database_path = str(tmp_path / "bangui_lock.db")
    connection_a = await open_db(database_path)
    try:
        await connection_a.execute(
            "CREATE TABLE IF NOT EXISTS test_lock (id INTEGER PRIMARY KEY, value TEXT);"
        )
        await connection_a.commit()

        await connection_a.execute("BEGIN EXCLUSIVE;")

        async def write_after_lock() -> None:
            connection_b = await open_db(database_path)
            try:
                await connection_b.execute(
                    "INSERT INTO test_lock (value) VALUES ('locked');"
                )
                await connection_b.commit()
            finally:
                await connection_b.close()

        task = asyncio.create_task(write_after_lock())
        await asyncio.sleep(0.1)
        await connection_a.commit()
        await task

        async with connection_a.execute("SELECT value FROM test_lock;") as cursor:
            row = await cursor.fetchone()
        assert row is not None and row[0] == "locked"
    finally:
        await connection_a.close()


async def test_parse_migration_statements_single_statement() -> None:
    """Test parsing a single statement without comments."""
    script = "CREATE TABLE test (id INTEGER PRIMARY KEY);"
    statements = await _parse_migration_statements(script)
    assert len(statements) == 1
    assert statements[0] == "CREATE TABLE test (id INTEGER PRIMARY KEY)"


async def test_parse_migration_statements_multiple_statements() -> None:
    """Test parsing multiple statements separated by semicolons."""
    script = """
    CREATE TABLE test (id INTEGER PRIMARY KEY);
    CREATE INDEX idx_test ON test(id);
    """
    statements = await _parse_migration_statements(script)
    assert len(statements) == 2
    assert "CREATE TABLE test" in statements[0]
    assert "CREATE INDEX idx_test" in statements[1]


async def test_parse_migration_statements_with_line_comments() -> None:
    """Test parsing statements with line comments."""
    script = """
    -- This is a comment
    CREATE TABLE test (id INTEGER PRIMARY KEY);
    -- Another comment
    """
    statements = await _parse_migration_statements(script)
    assert len(statements) == 1
    assert "CREATE TABLE test" in statements[0]


async def test_parse_migration_statements_with_block_comments() -> None:
    """Test parsing statements with block comments."""
    script = """
    /* Block comment */
    CREATE TABLE test (id INTEGER PRIMARY KEY);
    /* Another block */
    """
    statements = await _parse_migration_statements(script)
    assert len(statements) == 1
    assert "CREATE TABLE test" in statements[0]


async def test_parse_migration_statements_with_string_literals() -> None:
    """Test parsing statements with string literals containing semicolons."""
    script = """
    CREATE TABLE test (id INTEGER PRIMARY KEY, data TEXT);
    INSERT INTO test (data) VALUES ('value; with; semicolons');
    """
    statements = await _parse_migration_statements(script)
    assert len(statements) == 2
    assert "CREATE TABLE test" in statements[0]
    assert "INSERT INTO test" in statements[1]
    assert "value; with; semicolons" in statements[1]


async def test_parse_migration_statements_with_escaped_quotes() -> None:
    """Test parsing statements with escaped quotes in string literals."""
    script = """
    INSERT INTO test (data) VALUES ('it''s a test');
    """
    statements = await _parse_migration_statements(script)
    assert len(statements) == 1
    assert "it''s a test" in statements[0]


async def test_apply_migration_is_atomic_success(tmp_path: Path) -> None:
    """Test that migration is atomic when all statements succeed."""
    database_path = str(tmp_path / "bangui_atomic.db")
    db = await open_db(database_path)
    try:
        # Initialize schema_migrations table
        await db.execute(
            "CREATE TABLE IF NOT EXISTS schema_migrations (version INTEGER PRIMARY KEY, migrated_at TEXT);"
        )
        await db.commit()

        # Apply a test migration
        await _apply_migration(db, 1)

        # Verify the migration was recorded
        async with db.execute(
            "SELECT version FROM schema_migrations WHERE version = 1;"
        ) as cursor:
            row = await cursor.fetchone()
        assert row is not None and row[0] == 1

        # Verify the schema tables exist
        async with db.execute(
            "SELECT name FROM sqlite_master WHERE type='table' AND name='settings';"
        ) as cursor:
            row = await cursor.fetchone()
        assert row is not None
    finally:
        await db.close()


async def test_apply_migration_is_atomic_rollback(tmp_path: Path) -> None:
    """Test that migration is rolled back when a statement fails.
    
    This test verifies that when an error occurs mid-migration, the
    transaction is rolled back and the schema_migrations table is NOT updated.
    """
    database_path = str(tmp_path / "bangui_rollback.db")
    db = await open_db(database_path)
    try:
        # Initialize schema_migrations table
        await db.execute(
            "CREATE TABLE IF NOT EXISTS schema_migrations (version INTEGER PRIMARY KEY, migrated_at TEXT);"
        )
        await db.commit()

        # Create a custom migration that will fail
        from app import db as db_module
        
        original_migrations = db_module._MIGRATIONS.copy()
        
        # Add a migration that will fail on the second statement
        db_module._MIGRATIONS[99] = """
        CREATE TABLE test_rollback (id INTEGER PRIMARY KEY);
        INSERT INTO nonexistent_table VALUES (1);
        """
        
        try:
            # Attempt migration; it should fail
            with pytest.raises(Exception):  # sqlite3 will raise an error
                await _apply_migration(db, 99)

            # Verify the migration was NOT recorded
            async with db.execute(
                "SELECT version FROM schema_migrations WHERE version = 99;"
            ) as cursor:
                row = await cursor.fetchone()
            assert row is None

            # Verify the test table was NOT created (rollback occurred)
            async with db.execute(
                "SELECT name FROM sqlite_master WHERE type='table' AND name='test_rollback';"
            ) as cursor:
                row = await cursor.fetchone()
            assert row is None
        finally:
            # Restore original migrations
            db_module._MIGRATIONS = original_migrations
    finally:
        await db.close()


async def test_init_db_idempotent(tmp_path: Path) -> None:
    """Test that init_db is idempotent."""
    database_path = str(tmp_path / "bangui_idempotent.db")
    db = await open_db(database_path)
    try:
        # Initialize once
        await init_db(db)

        # Get schema version
        async with db.execute(
            "SELECT MAX(version) FROM schema_migrations;"
        ) as cursor:
            row1 = await cursor.fetchone()

        # Initialize again (should be no-op)
        await init_db(db)

        # Verify schema version is unchanged
        async with db.execute(
            "SELECT MAX(version) FROM schema_migrations;"
        ) as cursor:
            row2 = await cursor.fetchone()

        assert row1 == row2
    finally:
        await db.close()